diff --git a/requirements.txt b/requirements.txt
index bb577d0ab..c8f2f8c08 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,3 +4,5 @@ PyYAML>=3.10
 docutils>=0.11
 cryptography!=1.3.0,>=1.0
 pyOpenSSL<15.0.0
+# Until https://github.com/eliben/pycparser/issues/147 is fixed 
+pycparser==2.13